摘要:

A bandpass-to-bandstop transformation employing a delay line is used to convert a transversal CCD lowpass filter to its highpass counterpart, obtaining a configuration that is less sensitive to fabrication errors than a direct transversal implementation. The performance of a prototype breadboard system confirms the feasibility of the concept.

DOI:10.1049/ij-ecs.1979.0008

出版商:IEE    

年代:1979

数据来源: IET

摘要:

A circuit comprising a digital memory and a d.a. convertor constitutes a cost-effective method of generating data-window waveforms having optimal frequency-domain equiripple sidelobes. 8-bit quantisation in the memory and harmonic distortion in the d.a. convertor limit the achievable peak/sidelobe ratio to about 51 dB for the near-in sidelobc, and 54 dB for the far-out sidelobes.

DOI:10.1049/ij-ecs.1979.0009

出版商:IEE    

年代:1979

数据来源: IET

摘要:

A new class of multiple-real-root equal-ripple (M.U.R.R.O.E.R.) polynomials is proposed for the design of RC-active filters by cascading 3rd-order blocks. With respect to the classical methods, this new technique allows reduction of the number of blocks or, alternatively, improvement of the attenuation performance. As a consequence, the proposed approach produces a reduction in the power consumption and in the intrinsic noise of the filter or, if the number of blocks has not been reduced, the resulting better attenuation performance allows component tolerances to relax.

DOI:10.1049/ij-ecs.1979.0010

出版商:IEE    

年代:1979

数据来源: IET

摘要:

The set of harmonically-related nonorthogonal triangle waves is shown to form a basis spanning the same function space representable by Fourier (trigonometric) series. The triangle function set is, further, equivalent to the trigonometric series in important convergence-completeness properties. The weights of this series, and the weights of the finite series having minimum mean-square error, are calculated directly without resort to optimisation or other iterative techniques. This basis function set is most attractive for digital signal representation because these functions can be conveniently generated in a digital context. Unused ‘time slots’ of time-shared digital filter sections are also easily diverted to real-time signal representation. Thus, depending on the application, triangle waves can provide ease of implementation while maintaining the convergence properties of trigonometric series. For coding applications, continuous-time and discrete-time triangular transforms for aperiodic and sampled signals can be enunciated. Several laboratory and computer-generated examples are given.

DOI:10.1049/ij-ecs.1979.0011

出版商:IEE    

年代:1979

数据来源: IET

摘要:

The behaviour of data-transmission systems, in particular p.a.m. systems, using partial-response signalling techniques in the presence of Gaussian and impulsive noise is investigated. Such an investigation permits a meaningful study of practical systems, because even if nonlinearity has not been added to the system, all real systems have a finite dynamic range of linear operation and act as a soft limiter with a highsaturation level. A 3rd-order polynomial device expressed byY = a1x + a2x3with an optimum nonlinearity resemblance is employed to suppress the large excursions of the impulsive noise. The effects of the nonlinearity on the partial-response signalling-systems behaviour is searched. An equaliser-design approach in the frequency domain is presented that includes the constraints of elimination of performance degradation owing to the nonlinearity and minimisation of the receiver-output noise power. Several partial-response signalling systems which are of practical interest are considered, and for each system the receiving-filter (equaliser) characteristics are obtained. Finally, the behaviour of standard p.a.m. systems and partial-response signalling systems in the presence of nonlinearity are compared.

DOI:10.1049/ij-ecs.1979.0012

出版商:IEE    

年代:1979

数据来源: IET

摘要:

Switched-capacitor (s.c.) networks are of great interest owing to their compatibility with m.o.s.i.c. technology. It is shown how s.c. networks can be derived directly from continuous activeRCnetworks. The corresponding network functions inzare obtained from those insby using a simple ‘p-transformation’. It is shown that s.c. networks can also be designed directly. The resulting networks are often more versatile than those derived from another circuit type or technology. Numerous examples of both approaches to s.c. network and filter design are given and experimental results presented. Excellent agreement between theory and practice has been obtained.

DOI:10.1049/ij-ecs.1979.0013

出版商:IEE    

年代:1979

数据来源: IET